docs: def extension(line, cell=None):
    """ Load an extension. Use %extension --help for more details. """
    parser = _commands.CommandParser(prog='%extension', description="""
  Load an extension into Datalab. Currently only mathjax is supported.
  """)
    subparser = parser.subcommand('mathjax', 'Enabled MathJaX support in Datalab.')
    subparser.set_defaults(ext='mathjax')
    parser.set_defaults(func=_extension)
    return _utils.handle_magic_line(line, cell, parser)